diff --git a/acme/autocert/cache_test.go b/acme/autocert/cache_test.go
index 6e1b88d..653b05b 100644
--- a/acme/autocert/cache_test.go
+++ b/acme/autocert/cache_test.go
@@ -21,6 +21,7 @@ func TestDirCache(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(dir)
 	dir = filepath.Join(dir, "certs") // a nonexistent dir
 	cache := DirCache(dir)
 	ctx := context.Background()